Half-Life 2 Walkthrough -> East Black Mesa
We continue to the junkyard. We receive the gravity gun from Alyx and learn how to attract and throw objects. When she climbs up the dais, we place one crate on top of another nearby and climb up to her. We continue on. We meet her robot dog:
He'll take boxes from the container and throw them. You need to catch them. Then Alyx will suggest a game of ball, which the robot will pull out from under a wooden spool with a large stone on it. You need to catch it and throw it to the robot or simply to the side.
The game will be interrupted by approaching enemies. Follow Alyx back to the airlock before the dump. The robot will also run there. When he opens the jammed door, follow Alyx, but a cave-in will prevent you from following her. She will shout for us to go to the coast through Ravenholm:
We go into the tunnel she mentioned. The robot will open the door. We make our way through the cluttered corridor to the shaft. We knock the lock off the door blocking the stairs leading up.